1. Field of the Invention
The present invention relates generally to organic light-emitting diodes (OLEDs), OLED displays, and a method for fabricating them.
2. Discussion of the Background
Previously, display technology for high definition (HD) devices, e.g., HD televisions and portable computers, had been dominated by liquid crystal displays (LCDs). However, the liquid crystal display is becoming less desirable with the development of organic light-emitting diodes (OLEDs). OLEDs make use of thin film materials which emit light when fed an electric current. Compared to LCDs, OLED displays are thinner, consume less power, offer a wider viewing angle, and have faster response time. They are particularly useful in devices with miniature display areas.
However, current fabrication methods of OLEDs are expensive, time consuming, and/or limited to certain applications. Such fabrication methods include high vacuum evaporation, spin casting, and high vacuum thermal deposition which are both expensive and time consuming. In addition, high vacuum thermal deposition is limited to fabrication of OLEDs with small molecules rather than polymers.
Polymer-based OLEDs have been fabricated using spin coating, a less expensive, but still time consuming method, such that patterning the OLEDs on a substrate in a single step is not possible. With larger displays, due to the multiple step patterning, uniformity of the OLEDs on the substrate becomes an issue. In addition, spin coating requires substrates having flat surfaces.
Recently, an ink-jet printing method has been developed to fabricate OLEDs using ink-jet printers which deposit the OLED materials on a substrate at a particular resolution similar to the method used by ink-jet printers to deposit ink on paper. However, such methods are currently limited to relatively low resolutions of 300 dpi, for example. This makes the technology unattractive in the fabrication of high definition OLED displays. Moreover, ink-jet printing fabrication is limited to flat surfaces and is time consuming because OLEDs are fabricated one at a time.